I was going from your comment where you said Sintered Metal in your first line! However like I stated usually and I have yet to see where DMLS is more expensive when created a tool insert for injection molding. Now I do agree if doing thousands of anything you will want to stay with Injection Molding even using a RP tool in possibly bronze alloy or even aluminum. Either of which can also be build using DMLS and even CNC. SLA resins have come a long way, it all depends on the end application right ! They have the term Additive Manufacturing now, depending on quantity you can save money but if having to do metal casting your tooling may be more expensive then the whole process for dmls. I agree there are certain times where DMLS is not the correct application and or process for certain projects, I'd be the first to tell you what would be your easiest and most inexpensive way!